Experimental study on the effects of brash ice on the water-exit dynamics of an underwater vehicle

To investigate the impact of brash ice on the dynamics of the water exit of an axisymmetric vehicle, an experimental study was conducted on the water exit of an axisymmetric vehicle in brash ice using a water tank, launching system, control system, data acquisition system, and high-speed camera system. The brash ice zone was modeled using actual observational data from the Antarctic marginal ice zone off Wilkes Land in late winter. Brash ice was created from polypropylene material, and the influence of brash ice on the dynamics of the waterexit of the vehicle is analyzed. The results show that the collapse of bubbles during water-exit of a vehicle in the presence of brash ice creates a state of eruption, which splashes upward from the shoulder to the center of the vehicle, and the underwater cavities undergo shrinkage and shedding. The effects of brash ice on the magnitude of the force and moment on the vehicle during the process are diverse and operate in different directions. The overall deflection angle is greater than that under ice-free conditions. As water-exit speed increases, the splash time becomes earlier, and the extent of the splash becomes more dispersive. In addition, pressure falls as the vehicle approaches the water surface, and the extent and magnitude of pressure fluctuation during the whole water-exit process becomes more severe.